Question

At 4^oC, water has minimum density and maximum volume.

• A. True
• B. False

Answer 1

The correct option is B

False

Usually, we observe that things expand on heating and contract on cooling.

Water also follows this rule most of the time. If we cool water at room temperature, say ${25}^{o}C$, it will contract and reduce in volume. Since the mass of the water remains the same and the volume reduces, the density will increase. This goes on till $4^{o}C$. So far so good.

But when water is cooled beyond $4^{o}C$ upto $0^{o}C$ , we observe something strange. The water begins to expand! And the density will decrease. This is against what we normally see with substances like metals. We call this the anomalous expansion of water.

Density increases from ${100}^{o}C$ to $4^{o}C$ and then decreases from $4^{o}C$ to $0^{o}C$. So, density is maximum at $4^{o}C$.